Carbs coming off, jetting Q/MPG issue

[CaseyJ955]

89 Royale 1300.

 

Ive had this bike for a year but put less than 500 mi on it. I laid it up for the winter to do some work on it so it's ready for spring. When I had it running it ran fine, starts and hot starts were fine, power seemed fine but MPG was bad, like 25mpg tops sort of bad. The only other ridability issue was a significant transient stumble/sputter right after op temp was reached, every time. This came and went within a minute and only happened once per ride.

 

I bought a set of new diaphragms from a UK seller, I'm going to pull the carbs and see what they look like inside when I install those. While Im in there I'll set float levels and check jetting. I'm not sure why the MPG was so bad, would 3 bad diaphragms really trash the MPG that much?

 

I found very little info on factory jetting, I found one breakdown that had 3 different jet sizes. So I'm going to check and make sure nobody rejetted at some point so OEM jet sizes for the 89, and also (like the Vmax for example, factory mains are 152.5 and it's a bit rich for most so 150 or even 147.5 usually gets better MPG and more power). Is there any such wisdom for the Venture? Mostly I'm trying to get the 40-ish MPG that I have read they should have.

 

What I have done so far since it's been sitting;

Delink brakes, added braided lines and R6 calipers front and rear. (old calipers were hanging a little bit)

New Dunlop E3s

Complete fork overhaul/progressives/bushings/new steering head bearings installed.

 

Will be adding an Ignitek and resistorless 1.2 ohm COPS off an old CBR, already have all the stuff but really want to figure out whats causing such poor MPG. So yea, a link to or any wisdom on suitable jetting possibilities or any other input for the horrible MPG. I have managed to dial in my Vmax, so that is the only experience I bring with these V4 mills and I know the Venture has almost the same carb with some pretty different jetting requirements. I know I sort of touched on this before but the carbs are coming off now so just looking for any borrowed smarts so I dont end up having to pull the rack over and over.

 

Thanks folks.

 

Tony

[MiCarl]

Bad diaphragms probably aren't the problem. They allow extra air. When I replaced my holey ones on my '89 my MPG dropped to about 33.

 

In my case I decided the jet needles were probably worn (no longer available). I put the Skydoc spacer kit in and got back to 40MPG. It was running a little hot so I shimmed the needles up 0.020" and cooled it down a little with no noticeable drop in mileage.

[Flyinfool]

The 25 MPG could be that you are running on 3 cylinders, these bikes run very smooth on 3 cyl. There have been new owners that went years before they found out that they never had 4 cyl running.

If a dead cylinder is ignition related then the new ignition and COP will / should fix it. Why spend a lot of time and possibly money trouble shooting something that you are going to replace anyhow.

 

It is also common to get reduced MPG for a while after getting it to run correctly because you tend to USE all the new found power for a while.

 

I can not help you on jetting, that falls under blue smoke and mirrors for me. When my carbs die I may just splurge and convert to EFI.

[CaseyJ955]

It makes sense, I rode my Vmax all day in the hills, even smoked a Harley, all on 3 cyl. This one passed the downpipe spit test which is how I nailed a bad COP connection on the Vmax leaving me with only 3 cyl. Your 100% correct, they run great on 3 cyl.

 

I'm going to guess it's probably carb related. The PO was the orig owner but still not sure if the carbs have been messed with. A place in Mitchel did all the work since the bike was new and they said they cant recall the carbs ever being off the bike. After all the years it's probably past time to open these things up and see whats inside. I'm sure float level is off if nothing else.

 

One thing I didnt do is synch up the carbs or play with the AF screws, no real attempts to tune it since it was fall, figured I would have all winter to do everything that needed done. MPG that bad was probably something more than a simple adjustment. I'm sure it's time to set the jets and maybe spend some time playing with the needles. I have a shim kit for the Vmax.

[cimmer]

Syncing the carbs does help but also check the caps on the vacuum ports as they can have cracks and leak also. With a sync tool it will also let you know if you have some vacuum issue with the carbs and if they have never been off then I would strongly suggest a good cleaning and rebuild. Sirius Consolidated, Inc in Canada, https://www.siriusconinc.com has carb kits and parts for our bikes and can supply most of the parts for the rebuild. The rest you will need to order from Yamaha as no one else has them and yes unfortunately the needle valves for the VR 1300 are not available.

Hope this helps some and good luck.

Rick F.

[CaseyJ955]

Syncing the carbs does help but also check the caps on the vacuum ports as they can have cracks and leak also. With a sync tool it will also let you know if you have some vacuum issue with the carbs and if they have never been off then I would strongly suggest a good cleaning and rebuild. Sirius Consolidated, Inc in Canada, https://www.siriusconinc.com has carb kits and parts for our bikes and can supply most of the parts for the rebuild. The rest you will need to order from Yamaha as no one else has them and yes unfortunately the needle valves for the VR 1300 are not available.

Hope this helps some and good luck.

Rick F.

 

Thank you for the guidance and the link. I'm optimistic that it wont need much but I'm prepared to order the kits if needed. If I need Needles I'm sure I can get some from a vendor on the Vmax site, maybe at least some good previously enjoyed ones. On the VMax I was able to open them up, swap jets, adjust floats and close them up and it runs too well for words. I just hope I'm that lucky here but it's 10 years older and has 4x the mileage. Something came up yesterday and today but I hope I have time to get too it this afternoon while it's so nice and warm out.

[CaseyJ955]

There it is, its nearly 70 deg today, may even get enough melt to get the Max out.

 

So I'm outside pulling the left upper fairing and carb rack and I noticed that the two drivers side carbs were not even fully seated into the intake boots, looks like they were at the half way mark. I'm going to guess that this may have had something to do with MPG, maybe a little. Seller said they were never off but clearly that is not the case. I'm going to go through the carbs inside tomorrow and see whats up as long as they are off.

 

The other thing I have is the left fairing removed because I wanted access to the throttle cable junction, the throttle action is fairly stiff, also figured I could reach and remove the OEM coils.

 

The question I have is when folks lube the cables, is it also customary to lube the wheels inside that plastic junction?

Is there a good link to how to lube the cables, I have one of those cable lube sprays with the chucks and wondering if they work well enough to lube from that plastic junction and force the lubricant upward or if I have to pull the cables from the loud handle and lube them downwards. I am searchtarding today because I didnt see a thread for this but if I missed it a link would rock. Thanks folks!

 

There, done hijacking my own thread

[snyper316]

I would assume when you disconnect grip side once you start lubing the cable when it gets to the end of the first cables it would get up inside that wheel... just a thought tho, I lubed mine with 0-20w oil and a baggie with a corner cut out. One set on throttle grip and the other set from the carbs. But they weren't connected in the first place. I was putting in a used set and couldn't see a better time to do this....

[CaseyJ955]

The bike shop was closed this morning when I went to town, and as always I go well out of my way to minimize my time in town so I headed to Tractor Supply and picked up some Liquid Wrench Chain and Cable Lube. I'll give that a shot since I cant seem too locate what I had before. Just gotta get in there and figure out how to expose the inner cables by the grip without tearing off the switchgear.

 

Got the carbs apart and found that someone had definitely been into these before. They were quite clean, jets as per OEM according to the excellent write-up I found here http://www.venturers.org/Tech_Library/?action=article&cat_id=001010&id=366 so nobody tried to get creative there. The needles look great, with my reading glasses and plenty of light I can barely see where they seat, and almost not even really. The rubber plugs are reasonably snug but there are trace amounts of some fine sediment between the rubber peg and the bore.

 

What it doesnt cover is dry setting float levels. When I did my Vmax I used this page. http://www.factorypro.com/Prod_Pages/prody11.html

Would this page also be applicable for the Venture carbs? I was thinking so but would love to hear it from someone with some Venture experience. I will get into wet levels and such when I do the Vmaxization next year and have more space and stuff to do it. Setting the dry float levels made a profound difference in both performance and MPG on the Vmax and they were adjusted exactly as in the first pic so I adjusted them with a caliper and they looked just like the 2nd pic when I was done. As always, input welcome.

 

Thanks!!

[MiCarl]

The place to measure is the same. The measurement I've seen is 1".

 

Ideally you check the fuel level after.

[CaseyJ955]

The place to measure is the same. The measurement I've seen is 1".

 

Ideally you check the fuel level after.

 

IIRC I set the max to 1.125 or something. 1" would be a tad richer but I realize it's a pretty different state of tune. I take a measurement in the morning and see where it is currently.

 

If I dont get my MPG back or it runs poorly I'll go into wet levels but I'm going to be doing this all again next year when I rejet everything for the hi-flow heads and cams.

[MiCarl]

Since you're measuring from the bottom 1" would be leaner, not richer.

 

Still, 0.125" isn't your problem.

[CaseyJ955]

Since you're measuring from the bottom 1" would be leaner, not richer.

 

Still, 0.125" isn't your problem.

 

I had to go look at it, I was thinking it backwards for some reason. I'll go with 1" as lean should work just fine. I'm really thinking that the MPG issue may have been that the carbs were not fully seated into the intakes and the jet block plugs could stand to be more snug so I'll get some of those, dry set the floats and see what happens. Theres been quite a break in the weather so I'm hoping I can get the carbs back on and the Ignitek and COPs done before the snow returns.

 

EDIT,

 

I'm looking at it again, on the FP site it shows the measurement being taken from the top of the bowl to the corner of the float with the float resting on the needle. I think 1" would be richer if measured from the top as they show, but leaner measured from the bottom. As soon as I get some jet block plugs I'll be ready to put it all together.

Edited February 18, 2017 by CaseyJ955

[MiCarl]

You're right.

 

I should have looked at the pictures again.....

[cimmer]

yes just as the picture shows on the website, http://www.factorypro.com/Prod_Pages/prody11.html, the casting circle on the jet in the lower middle is like the picture shows. the cut out on the float is level with the top of the circle. The upper right circle bottom is level with the top of the float. This is a good starting point for setting the float level.

Rick F.

[CaseyJ955]

I know Sean Morley has done some Venture stuff so when I priced out the jet block plugs I asked about Venture float adjustment. He said he sets Venture floats using identical measurement and procedure as Vmax so I'll give that a shot. When I did the Vmax I painstakingly set them all at 1.125" per that site and the cutout did land perfectly on that stamping on each carb, they were all identical.

 

I think after I get them together I'll follow the procedure to check wet levels. I want to keep it on the leanest side of acceptable as I can, both for MPG and because my elevation is ~3400' and much of my riding goes up considerably from there.

 

Thanks all for the responses. I'll be giving this a go and check back in with the results.